1. Field of the Invention
This invention relates to a piezoelectric actuators, and more particular for actuating control valves or injection valves of internal combustion engines in motor vehicles, and having a circular, cylindrical piezoelectric actuator body in the form of a multilayered laminate made up of stacked layers of piezoelectric material with intervening metallic or electrically conductive, alternating first and second electrode layers that function as electrodes, wherein these first and second electrode layers alternatingly contact a first and second electrically conductive common electrode connection.
2. Description of the Prior Art
Generally, high-voltage piezoelectric actuators that are cylindrical in shape are known which, as individual disks with fixed electrodes, are stacked into a cylinder (e.g. see U.S. Pat. No. 4,460,842). For the external electrode connections, electrode plates are routed to the circumference of the cylindrical stack and are bent at right angles there so that strip-shaped electrode connections that are angularly offset from one another can contact the respective electrodes that are associated with one another.
For the use of a piezoelectric actuator for actuating injection valves in internal combustion engines of motor vehicles, a cylindrical actuator is advantageous since it optimally utilizes the available installation space in an injector body and in a circular bore in the cylinder head of the engine. Then a high-pressure bore can also be routed in the injector body or housing next to the actuator.
The circular contour of the actuator body requires a special electrode structure in order to be able to embody an electrically and mechanically favorable contacting of the electrodes with associated electrode connections.